Immunogenic ribosomes have been isolated from Salmonella typhimurium and Group A, Type 14 Streptococcus pyogenes. Current research involves the following: 1) the isolation of a single immunogenic ribosomal protein from S. typhimurium and determination of the nature of the immune response elicited by the ribosomal immunogen; 2) isolation of ribosomal RNA and protein from Streptococcus pyogenes to determine the immunogenic moiety of the ribosomes; 3) studies on the specificity of the immune response to the ribosomal immunogen isolated from Streptococcus pyogenes; 4) long term experiments to determine the duration of the immune response elicited by whole ribosomes isolated from S. typhimurium and Streptococcus pyogenes.